Help me in building a crossbow build

[Mystic Iris]

I am interested in playing a crossbow user that is primarily using some sort of dot: preferably bleeding or poison/acid, something with pierce can be good too. I am not interested in some sort of elemental damage or mainly caster spells. So, which classes could make for a strong build that won't get dropped easily on ultimate? I have my eyes on:
- bleed/pierce trickster (shaman + nightblade)
- bleed ritualist (shaman + necro)
- bleeding warder (shaman + soldier)
- pierce/int. trauma commando (soldier + demo)
Building a poison crossbow build seems fairly difficult. I definitely do not want to regret my class choice again after reaching level 100. I know there are people with far more experience and expertise of Grim Dawn than me who hopefully can provide feedback here. So if you have any suggestions, I'd love to hear them.

[sarcastic_godot]

Conjurer (Shaman + Occultist)?

I'm currently playing one as caster, and was pondering quite exactly this... ...and have to admit that I'm _not_ one of the brain trust. So consider this rather as a co-submission to your poison-crossbow question...

Shaman contributes Vines to keep them at a distance (and chomp up the mass trash), the 2Hdd buffs, and Savagery (with Tenacity of the Boar for OA/DA) for your Xbow. Occultist contributes Curse of Frailty and Bloody Pox as debuffs + dmg, and Blood of Dreeg and Possession as buffs. Much bleed/poison with decent synergy. A bit tight on the skill points, though... ...will need quite some MinMax fine tuning... ...or stopping investment into the Shaman bar at 32.

Devotions would be Rat, Akeron's Scorpion (Feral Hunger) [or Fox if you want to go more into bleeding], Eye of the Guardian (Bloody Pox), Bat (Grasping Vines), Ghoul (Blood of Dreeg), Manticore (Upheaval), Hydra or Spider, Abomination (partial, left claw only, liked to Savagery), and Huntress (Curse of Frailty).

You'll note that with the devotions on the two-handed passives and Savagery, you'll get a nice target-centered toxic/noxic AoE.

Playstyle: Vines to CC the mobs, CoF + Bloody Pox to debuff, then bayonet ... er, oops, no... bolt the wounded. Recast Vines + Pox as needed...

This would be my take, I'd already have Malady and Sangvinar, both un- as well as empowered, for leveling, and would aim for the (Mythical) Quillthrower of Dreeg as end gear... ...and the maybe Deception of Dreeg set (4/5), but that's far future for now...

A tentative, ungeared build would be: https://www.grimtools.com/calc/xZy933qZ

[Halcyon]

Best Crossbow IMO is the Mythical Harbinger of Eternal Suffering, but it deals Chaos damage which has no affiliated DoT so it doesn't really fit your brief.

Instead, I'd point you to the Mythical Quillthrower of Dreeg which supports acid/poison and is best used by Nightblade/Occultist (aka Witch Hunter). Witch Hunters aiming to do acid/poison Blade Burst can also use the easily farmed Ugdenbog Bilelauncher for levelling.

This build would focus on Blade Burst as primary attack with debuff support from veil of shadow/night's chill and curse of frailty/vulnerability. Blood of Dreeg provides a heal and self buff. There aren't too many skills soaking up skill points so you can build passives like merciless repertoire, phantasmal armor, and possession to max.

Constellations of note would be Manticore, Murmur, Scorpion, Eye of the Guardian, kraken, ghoul, maybe yugol or abomination too.

[Mystic Iris]

How about this Crossbow Commando:
https://www.grimtools.com/calc/RZROj14N
Could use some feedback on this build.

[Halcyon]

Taking a look now, there are some immediate red flags.

Resists are not maxed. This is mandatory.
Spirit is too low to equip your jewelry, you need at least 387 for the items you have equipped.
No lifesteal (use seal of blades instead of seal of might)

Questionable skills:
Maxed Veterancy
Maxed Grenado line on a piercing attacker build
Counterstrike on a ranged build with no retaliation focus
only 4 points in blast shield, why not 5 for 1% more resist max?
low Flame Touched, you could get a lot more damage and OA out of it

Questionable other stuff:
why no 4th valdun piece? The full set bonus is awesome and you don't really need the +3 to all skills for an autoattacker
devotions are not super, though not awful either
choice of movement rune, I assume this is what you have available not what you'd like to have?
You have a ton of physical damage buffs but deal only piercing damage, legs, belt, gloves, shoulders, relic, menhirian ring, all are physical focused.